Message contains NUL characters - howto dump?
cyrus at puri.jet2web.at
Wed Apr 15 10:18:46 EDT 2009
I have a problem with one of our customers.
When he forwards an email with the thunderbird email client (windows version), the lmtp-daemon on my cyrus-imapd (v2.3.13) rejects those emails with the error "554 5.6.0 Message contains NUL characters".
...ok, that's clear, there are "NUL" characters in the email.
But I would show my customer, where the "NUL" character is.
For tests, I generate a testmail, with "echo -e "From:<sender at example.com>\nTo:<recipient at example.com>\nSubject: test\n\ntest\0000test\n.\n" > mail_with_NUL.txt
Now I dump the lmtp-session on the cyrus-imapd host with:
tcpdump -vv -XX -s 65535 -n -i eth1 "port lmtp
and I see the "NUL" character:
0x0230: 7065 6564 2e61 740d 0a0d 0a74 6573 7400 peed.at....test.
0x0240: 7465 7374 0d0a 2e0d 0a test.....
65 = e
73 = s
74 = t
00 = NUL
...ok, fine, I can find the "NUL" character.
But when I dump the lmtp-session with the customer email (which get's the error "554 5.6.0 Message contains NUL characters"), I cannot find this "NUL" character.
Can someone tell me, what I did wrong?
Thanks in advance.
More information about the Info-cyrus